Numerous automated clinical analyzers are known and widely used in hospital clinical laboratories. The majority of such analyzers can be categorized into two distinct groups of either single-channel "batch" type analyzers or multi-channel "profile" type analyzers. Batch type analyzers are adapted to test for a single constituent in each of multiple samples loaded into the instrument. An example of such an instrument is illustrated in U.S. Pat. No. 3,748,044 issued to the same inventor herein. By contrast, profile type analyzers simultaneously test for a fixed number of predetermined different constituents in each of multiple samples loaded into the instrument. Such testing for multiple constituents is generally accomplished by dividing the sample and passing these portions through separate and discrete analysis stations or channels (hence the designation "multi-channel"). Each of these analysis stations is generally dedicated to testing the sample for a particular constituent.
Both the batch and profile type analyzers generally utilize a liquid reagent with the particular constituent being tested in the sample and a photo-optical system to read the optical absorbance of the sample which corresponds to the level of the constituent in the sample.
Although each of these types of automated analyzers have received wide acceptance in the clinical laboratory, certain drawbacks are associated with their use. For example, although the batch type analyzer is reliable due to its simplicity, cost effective for large number of samples and has a relatively high test throughout rate, it is limited in the sense that it can only be effectively utilized to perform a single constituent analysis at a time on a relatively large number of samples. In addition, such analyzers are not capable of performing emergency "stat" tests due to their relatively long and complex set up time and their inherent inability to economically analyze a single test sample.
Profile type analyzers are similarly limited in their ability to perform emergency "stat+ tests. A further significant disadvantage found with profile type analyzers is that although they can simultaneously perform tests for multiple constituents on the same sample, generally all of these tests must be performed for every sample whether desired or not. This results in a waste of both sample material and the reagents used in the unnecessary tests. Furthermore, due to the fact that multiple discrete and dedicated channels are utilized in such an instrument, there is significant duplication of numerous components which adds to the complexity and expense of the overall instrument.